1. Field of the Invention
The present invention relates to a vehicle control device which activates a camber angle adjustment device to control a camber angle of a wheel for a vehicle including the wheel and the camber angle adjustment device which adjusts the camber angle of the wheel. More particularly, the present invention relates to a vehicle control device which can provide compatibility between high grip performance and fuel efficiency.
2. Description of the Related Art
Attempts have been made to sufficiently bring out the capability of a tire to improve the turning performance by providing a large camber angle (angle formed by the center line of a tire and the ground) of a wheel in a minus direction. This is because, when the camber angle is set to 0° for example, a tread contacts the ground in the entire region in the width direction during straight-ahead driving, while the tread on the inside is caused to float from the ground by the inclination of the vehicle due to the centrifugal force at the time of turning whereby a sufficient turning performance cannot be obtained. Thus, by providing the camber angle in the minus direction in advance, the tread can contact the ground in a large width at the time of turning, whereby the turning performance can be improved.
However, although the turning performance of the tire is improved when the wheel is mounted to the vehicle at a large camber angle in the minus direction, the ground contact pressure on a tread end portion on the inside during the straight-ahead driving is increased whereby there has been a problem that the tire is worn uneconomically and the temperature in the tread end portion increases.
Thus, Japanese Patent Application Publication No. JP-A-2-185802 discloses technology of providing high rigidity by reinforcing a side portion on one side of a tire to be stronger than a side portion on the other side, and ensuring wear resistance, heat resistance, and high grip performance by dividing tread rubber into two such that the hardness is lower on one side than the other side or increasing the tread thickness in a tread end portion, in the case where a wheel is mounted to a vehicle at a large camber angle in a minus direction.
Also, U.S. Pat. No. 6,347,802 B1 discloses a suspension system which performs an active control of a camber angle of a wheel by the driving force of an actuator.
However, in the former technology, there has been a problem that the compatibility between high grip performance and fuel efficiency (low rolling resistance) has been insufficient, although sufficient performance can be obtained in maintaining the high grip performance at the time of turning. In the related-art technology described above, the high grip performance is limited to the time of turning, and there has been a problem that the high grip performance cannot be sufficiently obtained at a sudden acceleration or a sudden brake during the straight-ahead driving, for example. In the same manner, in the latter technology, there has been a problem that the compatibility between the high grip performance and fuel efficiency is insufficient.